In semiconductor processing, a silicon wafer or other type of flat workpiece is exposed to sequence of processes to form layers and pattern of conductive and dielectric materials. These materials make up the transistors, connections, and other components of the eventual semiconductor die. The processes are performed in several different processing chambers. A chuck, carrier, pedestal, or another type of holder is used to hold the wafer as it is moved between chambers. The wafer may be carried by one carrier and then transferred to another carrier as it moves from one process to another.
An electrostatic chuck (ESC) is widely used as a holder to clamp on to a silicon or similar type of dielectric wafer in semiconductor plasma process chambers. The ESC uses an electrostatic force to grip the wafer during plasma and during other types of processes. At the end of a process or when the wafer is to be transferred to a different carrier, the electrostatic charge is discharged so that the wafer can be released from the ESC.
A two-step voltage sequence is sometimes used to de-chuck a wafer. The voltage sequence is to eliminate the electrostatic charge of the chuck that is applied to the wafer. The voltage sequence may be combined with a gentle helium gas pressure against the back side of the wafer to push it away from the chuck.